Keep pushing for the MIG details and ALL other documentation which they have not sent you to date - there's a list of the documents you should be asking for on the site somewhere.(posted 8050 days ago)To make that piece of paper a deed, amongst other things, there must be a proper seal next to your signatures. The mortgage conditions form part of that deed. Request a copy and ask them to explain why they didn't enclosed a copy with it.
The wording in the conditions may (or may not) give a clue as to speciality/simple debt.
Good luck